Why the blaring megaphones in Pakistan?

I am troubled by the sheer volume of the megaphone (loud speaker as they call them) all over mosques in Lahore and other cities. How did this become a custom and practice in Islam to blare out sermons and call to prayer at well above 100dBA? Most will agree that even sounds at 85dBA (decibels) in public places is considered obnoxious and harmful. I have experienced two or three mosques in the same general vicinity blaring away at ear-splitting volume simultaneously. Once a sweet call of the muezzin is now a jumble of competing megaphones. I would like to know how this culture developed and why nothing is being done about this noise pollution.